Straight Bevel Gear – M3 to M12, DIN6-9, Multi-Material

Understanding the tapered tooth geometry is the starting point for correctly mounting and loading a straight bevel gear pair. Several terms define the geometry:

DIN gear accuracy grades define the permissible error in tooth spacing, profile form, pitch variation, and runout. For straight bevel gears, a lower DIN grade number means tighter tolerances and better accuracy. The four grades available from Korea Ever-Power cover the practical range from precision servo drives down to general-purpose power transmission:

The standard workhorse material for industrial straight bevel gears. Good machinability, adequate strength for moderate load applications, and widely available in the module range M3–M12. Can be normalised, through-hardened, or induction-hardened depending on load and wear requirements. Not suitable for corrosive environments without surface protection.

Best for: general industrial drives, agricultural machinery, conveyor heads, power tools at moderate speed

Higher load capacity than C45 through the combination of alloy content and heat treatment response. Case-hardening grades (20CrMnTi) produce a hard case over a tough core; through-hardening grades (42CrMo) provide uniform hardness. The correct grade depends on whether impact resistance (favour case-hardening) or dimensional stability after hardening (favour through-hardening) is the priority.

Best for: automotive differentials, heavy industrial machinery, high-load farm equipment, marine drives

For environments where corrosion resistance takes priority over maximum load capacity. 304 suits most food and pharmaceutical drives; 316 adds molybdenum for chloride resistance in wash-down and marine environments. Surface passivation after machining optimises the corrosion resistance of the passive oxide layer. Load rating is lower than alloy steel at equivalent module — upsize module or increase face width if the application requires higher torque in stainless.

Best for: food processing, medical equipment, pharmaceutical packaging, marine drives, laboratory instruments

Brass machines to tight tolerances, runs quietly against a steel driver gear, and resists corrosion in atmospheric and humid environments. Copper alloys are used in specific electrical and thermal applications where the material's conductivity is also needed. Both are non-sparking, which is relevant in hazardous atmosphere environments. Load capacity is modest — typically used for instruments, light industrial and commercial drives.

Best for: instrumentation, consumer products, light industrial drives, hazardous atmosphere environments

Aluminium bevel gears are chosen where minimum weight is a design constraint — robotics, aerospace auxiliary mechanisms, and portable machinery. The material's low density, excellent machinability, and good corrosion resistance (anodised) make it suitable for moderate loads at moderate speeds. Anodising the finished gear increases surface hardness and provides corrosion protection simultaneously.

Best for: robotics, portable machinery, lightweight automation, aerospace auxiliary drives

POM straight bevel gears run quietly, require minimal lubrication, and resist many chemical environments that would corrode metal gears. Their light weight and low friction make them suitable for consumer electronics, office equipment, light instrumentation, and small actuators. Operating temperature should stay below 80–90°C; beyond this, POM softens and dimensional stability degrades. Load capacity is low — use a larger module than an equivalent steel gear for the same torque.

Best for: office equipment, consumer electronics, light actuators, chemical-resistant drives, no-lube applications

Korea Ever-Power applies a full quality assurance sequence to straight bevel gear production. The following tests and documents are issued with every order:

1. Chemical composition report — mill certificate and independent spectral analysis confirming the steel grade matches the specified material before any machining begins. Raw material entering production without this verification does not proceed.
2. Mechanical performance report — tensile strength, yield strength, elongation, and impact toughness test results on test pieces from the same heat as the production parts. Critical for gears intended for load-bearing applications in automotive, construction, or power generation.
3. Ultrasonic test (UT) — 100% ultrasonic inspection per EN 10228-3, SA388, or the customer's specified standard. UT detects internal voids, inclusions, and laminar defects in the gear blank that surface inspection cannot find and that could cause premature fracture under load. This is standard for safety-critical and aerospace-adjacent applications.
4. Heat treatment report — original time-temperature curve from the heat treatment furnace confirming that the carburising or hardening cycle reached the specified temperature, held for the correct duration, and quenched at the correct rate. Retained per batch for traceability.
5. Dimensional inspection report — CMM measurement of critical tooth geometry parameters (pitch cone angle, tooth spacing error, runout, back-cone distance) and mechanical dimensions (bore, OD, face width, hub geometry) compared against the drawing tolerances. Any non-conformance is quarantined before shipment.

Automotive

Differential gears in rear-wheel drive vehicles, transfer cases in 4WD systems, and auxiliary drives for power steering and HVAC compressors. The automotive sector demands tight production tolerances, consistent heat treatment, and full material traceability — all provided as standard with Korea Ever-Power automotive-grade bevel gears.

Industrial Machinery

Machine tools, printing presses, conveyors, and packaging equipment all use straight bevel gears to transmit power at right angles between shafts that cannot be co-axially aligned. The gear's ability to handle both constant and cyclic loads makes it the reliable choice for production machinery running multiple shifts.

Power Generation

Wind turbine yaw and pitch drives, hydroelectric auxiliary systems, and solar tracker drives use straight bevel gears for low-to-moderate speed angular transmission. The UT inspection and full material certification routinely required for power generation contracts are standard documentation in Korea Ever-Power's QA package.

Agricultural Machinery

Tractors, combines, and harvesters use straight bevel gears in PTO drives, header gearboxes, and steering mechanisms. The intermittent-duty and moderate-speed nature of most agricultural drives makes the straight tooth profile entirely suitable, and the simpler manufacturing versus spiral bevel keeps replacement costs accessible for farm equipment owners.

Construction & Marine

Excavator final drives, crane slewing mechanisms, and marine propulsion angle drives rely on large-module straight bevel gears in alloy steel with full UT certification. Stainless grades serve marine auxiliary machinery in contact with seawater-contaminated environments. Physical size and load ratings in these sectors often require custom modules and non-standard gear geometries.

Automation & Semi-Conductor

Robotic wrist joints, wafer-handling robots, and automated parking systems use small-module straight bevel gears in aluminium, stainless, or POM. In semi-conductor applications, material purity and particle generation are critical — electropolished stainless or anodised aluminium versions are specified where contamination risk must be minimised.

Everything on your site is made to order — does that mean I cannot get a straight bevel gear quickly?

Made-to-order production allows us to confirm your exact bore, module, and material before cutting begins, which eliminates the dimensional mismatch problems that arise when adapting a stocked part to a housing it was not designed for. For straight bevel gears in common modules (M3, M4, M5, M8) in C45 steel, our lead times are competitive with distributor stock for custom dimensions. For urgent requirements, please contact our team with the module, tooth count, bore, and material and we will confirm the fastest available schedule.

I cannot identify the module of my worn gear. What should I send you?

The best approach is to send us the worn gear itself — Korea Ever-Power specialises in reverse engineering from physical samples. If sending the gear is not practical, provide: a photograph showing the tooth profile at the large end; the outer (large-end) diameter; the tooth count; the hub diameter; the hub length; the face width; and the bore diameter. From these measurements our engineering team can calculate the module, identify the gear series, and prepare a quotation. Worn teeth tend to give a slightly low module reading from the outer diameter method, so sending the sample is the most reliable approach when the original drawing is not available.

What is the difference between milled, hardened, and ground tooth treatments?

Milled teeth are produced by the gear cutting machine and used in the as-cut condition — no further tooth finishing is performed. This is the baseline for DIN 8–9 grades and is appropriate for low-to-moderate speed, general-purpose drives. Hardened teeth are milled first and then subjected to heat treatment (carburising and quenching, or through-hardening) to increase surface hardness and wear resistance; heat treatment introduces some dimensional distortion that slightly degrades accuracy class relative to the pre-hardened state. Ground teeth are produced by gear grinding after hardening, correcting the distortion and delivering the highest accuracy class — DIN 6 or DIN 7 — at the cost of additional machining time. Choose the treatment based on the required accuracy grade and the load level: light load and low speed typically do not justify the cost of grinding; high load and higher accuracy requirements do.

Can you manufacture metric straight bevel gears to non-DIN standards such as JIS or ANSI?

Yes. Korea Ever-Power holds tooling and process documentation for ISO, DIN, ANSI, JIS, BS, and non-standard bevel gear production. Metric module gears per JIS B 1704 and inch diametral pitch gears per ANSI/AGMA 2003 are both within our production capability. If you specify the standard on your enquiry drawing, we will confirm coverage and any tool procurement requirements before order placement. For non-standard configurations — custom module, non-standard intersection angle, or unconventional tooth geometry — submit the drawing and we will review feasibility within two working days.

Is ultrasonic testing mandatory or optional on Korea Ever-Power straight bevel gears?

Ultrasonic testing (UT) per EN 10228-3 or SA388 is a selectable option at the quotation stage, not a mandatory addition to every order. It is specified for safety-critical, pressure-vessel-adjacent, and aerospace-adjacent applications where internal material defects must be ruled out before the part enters service. For standard industrial drives — conveyors, agricultural equipment, general machinery — the chemical composition report and hardness verification are typically sufficient. If your application requires UT, specify the applicable standard (EN 10228-3 for wrought steels, SA388 for large forgings, or your customer-specified standard) in the enquiry and we will include it in the QA scope and adjust the lead time accordingly.

Can straight bevel gears be customised with special surface coatings or treatments?

Yes. Korea Ever-Power offers a comprehensive range of surface finishes beyond the standard phosphating and black oxide: zinc plating (hot-dip or electroplated), nickel plating, Dacromet, Geomet, powder coating, electrophoresis, and anodisation for aluminium gears. Each surface treatment adds a small dimensional layer that must be accounted for in the bore and mating face tolerances — specify any surface treatment at the drawing stage so we can apply the appropriate pre-treatment dimensions. For gears in food-contact or pharmaceutical environments, passivation after machining is the correct treatment for stainless steel, and we can provide the passivation certificate with the shipment. Contact our team with your surface treatment requirement and we will confirm suitability and lead time.

"We replaced straight bevel gears in a series of agricultural PTO drives. The original gears were C45, DIN 8, and Ever-Power matched the specification exactly. Full material certification and the heat treatment report gave us the documentation we needed for our ISO quality audit. Gears have been running through two harvest seasons with no wear issues."

Park Seung-cheol  |  Procurement Manager, Jeonbuk Agricultural Machinery  ·  Q2 2025

"We specified M5 alloy steel straight bevel gears with UT inspection for a wind turbine yaw auxiliary drive. The EN 10228-3 UT report came with the delivery as promised. Dimensional report matched our incoming inspection on every piece. This level of documentation is what our turbine OEM customer requires and Ever-Power delivered it without issue."

Kwon Tae-min  |  Component Engineer, Gyeongnam Wind Energy Systems  ·  Q4 2025

"We sent Ever-Power a worn straight bevel gear from a packaging machine with no drawing — just the sample and the outer diameter and tooth count measured by our maintenance team. They identified the module correctly, produced the replacement in 316L stainless for our food-contact application, and included a passivation certificate. Fitted first time with no housing modification."

Kim Yu-ri  |  Engineering Supervisor, Chungnam Food Packaging Lines  ·  Q1 2026

"We designed a parking system using M3 aluminium straight bevel gears to keep weight down. Ever-Power produced anodised aluminium versions to our DIN 7 drawing. The anodising dimensional allowance was factored in correctly — the finished bore was within 0.01 mm of the nominal. Noise level in the installed system is within our product specification."

Lee Chang-ho  |  Mechanical Designer, Seoul Smart Parking Systems  ·  Q3 2025

"We produce semi-conductor wafer handlers that use miniature POM straight bevel gears in a cleanroom environment. Ever-Power produced M3 POM gears to our ANSI drawing with the bore and hub geometry we needed. Particle generation in testing was below our cleanroom threshold. The gears have been running in the handler for eight months without measurable wear."

Choi Byeong-hun  |  Automation Engineer, Suwon Semi-Conductor Equipment Co.  ·  Q2 2025